Even a fake grin may help lower heart rate in stressful situations

By Michelle Castillo

Updated on: July 31, 2012 / 1:37 PM
/ CBS News

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(CBS News) A fake smile might be better for you than no grin at all, according to a new study.

Researchers at the University of Kansas discovered that if people were told to hold a facial position similar to smiling - whether they knew they were supposed to be grinning or not - they had lower heart rates after a stressful situation.

"This is not going to cure you if you have chronic stress or a major life event like a tornado," Dr. Sarah Pressman, assistant professor of psychology and co-author of the study, told HealthPop. "But, it's almost impossible to be really angry or really stressed with this big smile on your face.... You can't help but reduce that negative effect."

For the study, 169 college-aged subjects, equally split between men and women, were trained to hold chopsticks in certain ways with their mouth either to mimic a neutral facial expression, a standard smile or a Duchenne smile, a genuine smile that uses muscles both in the mouth and the eyes. Half of the smiling group were told that the facial expression was "kind of like a smile," Pressman explained. Everyone else was just told to hold the chopsticks in that specific position.

Then, the subjects were told they would be taking part in multi-tasking activities, but the intention was really to put them through stressful situations. While holding the chopsticks with their mouth, they had to perform tasks like putting their hand in ice water or tracing a star using with their non-dominant hand while looking at the reflection in a mirror.

During and after, the subject's heart rates were recorded. Those who held the chopsticks in a smile position, particularly those who held a Duchenne smile, had lower heart rates after a recovery period than those who had neutral expressions. Those that were told they were supposed to be smiling had a slightly higher increase in decreased heart rate compared to the group that didn't know they were smiling.

Pressman said that lower blood pressure was also observed in general, but not in every case. The results from the blood pressure measurements were similar in the fact they were lower, but not statistically significant.

Heart rates, or the number of times a heart beats per minute, normally quickens or even skip beats during stressful situations, according to the National Institutes of Health. The Mayo Clinic points out that decreased heart rates and blood pressure can indicate a person is more relaxed.

In the future, Pressman and her colleagues want to expand the study to see if a smile - fake or real - in less stressful situations can create a more positive mood. Previous research has shown that people who are told to hold a smiling position with their face, and then told to look at cartoons were more likely to rate the cartoons as funnier than people who had a neutral expression, Pressman said.

Other research has shown, however, that people who are required to smile all day for their job can have a negative effect on their mood, Pressman pointed out.

"There probably is a time limit, but if you want to undo physical razzle, (smiling) will probably help," she stated.